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ME 101

ENGINEERING GRAPHICS

Dr. Ouzhan YILMAZ (Assist.Prof.)Mechanical Engineering Department

Room: 319

[email protected]

http://www.gantep.edu.tr/~oyilmaz

The University of Gaziantep

Isometric Drawing

Faculty of Engineering


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Introduction and Objectives

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

This lecture introduces the concept of Isometric projection and Isometricdrawing of an object.

Followings will be highlighted to be able to explain the Isometric drawing:

Axonometric projection

Isometric projection

Isometric drawing Isometric and non-isometric lines (Boxing and offset methods)

Angles in isometric drawing

Curves in isometric drawing

Circles in isometric drawing (Four center ellipse)

Isometric circle arcs

Students are required to understand the fundamentals of isometric drawing

and the technical and practical details while drawing of an object.


3/27

Axonometric Projection

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

AB

CD

Parallel & normal

to picture plane

Line

of

sight A

B

CD

Is a parallel projection technique

used to create a pictorial drawing of an

object by rotating the object on an axis

relative a projection or picture plane.

Axonometric projection is one of the

four principal projection techniques:

multiview, axonometric, oblique and

perspective


4/27

Axonometric Projection

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

In Multi views andaxonometric

projections, the

lines of sight are

perpendicular to the

plane of projection;

therefore, both are

considered

orthographic

projections


5/27

Axonometric ProjectionType of axonometric drawing

a

b c2. Dimetric Two angles are equal.

b

a

c3. Trimetric None of angles are

equal.

a

b c1. Isometric All angles are equal.

A

B

CDA

B

C

D

Axonometric axis

Axonometric axis

Axonometric axis

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing


6/27

Isometric Projection

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

Rotate 45

about vertical axis

Tilt forward(35o16)

All edges foreshortenabout 0.8 time.

An isometric projection is a

true representation of the

isometric view of an object.


7/27

Isometric Drawing

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

Isometric projection(True projection)

Isometric drawing(Full scale)

Forshorten

Full scale

Isometric drawing is a drawing drawn on an isometric axes using ful l scale.

Isometric drawings are almost always preferred over isometric projection forengineering drawings, because they are easier to produce

I i D i


8/27

Isometric Axes

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

An isometric drawing is an axonometric pictorial drawing forwhich the angle

between each axis equals 120 degrees and the scale used is full scale

I t i D i


9/27

Positions of Isometric axes

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

Regular

isometricReverse axis

isometric

Long axis

isometric

View point is looking

down on the top of

the object.


up on the bottom of

the object.


from the right (or left)

of the object.

Isometric axes can be arbitrarily positioned to create different views of a

single object.

I t i D i


10/27

Selection of Isometric axes

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

View (a) is preferred as it reveals more detail than the others

ME 101Isometric Drawing


11/27

Isometric and Non-isometric lines & planes

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

In an isometric drawing, true length

distances can only be measured alongisometric lines, that is, lines that run

parallel to any of the isometric axes.

Any line that does not run parallel to an

isometric axis is called a non-isometric

line

Non-isometric lines include inclined and

oblique lines and can not be measured

directly. Instead they must be created by

locating two end points.



12/27

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing


The three faces of the isometriccube are isometric planes, because

they are parallel to the isometric

surfaces formed by any two

adjacent isometric axes.

Planes that are not parallel toany isometric plane are called non-

isometric planes



13/27


ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

Isometr ic l ineis the line that run parallelto any of the

isometric axes.

Isometric axes

True-length distances are shown along

isometric lines.

Nonisometric linesIsometric lines

Isometric planes



14/27

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

Isometric drawing

The Boxing-in Method for Creating Isometric Drawings

Thefour basic steps for creating an isometric drawing are:

1. Determine the isometric viewpoint that clearly depicts the features of the

object, then draw the isometric axes which will produce that view-point.

2. Construct isometric planes, using the overall width (W), height (H), and depth(D) of the object, such that the object will be totally enclosed in a box.

3. Locate details on the isometric planes.

4. Darken all visible lines, and eliminate hidden lines unless absolutely

necessary to describe the object.



15/27

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

Isometric sketching

from multi-view drawing

Top View

Front View

Side View

Bottom

Front

Side

Side

Front

Top

Regular

Reverse

WD

H

H

DW



16/27

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

Isometric drawing

STEPS

1. Positioning object.

2. Select isometric axis.

3. Sketch enclosing box.

4. Add details.

5. Darken visible lines.



17/27

ME 101

Dr. Ouzhan Ylmaz

Isometric Drawing

Isometric drawing

1. Positioning object.

2. Select isometric axis.

3. Sketch enclosing

box.4. Add details.

Note In isometric sketch/drawing), hidden lines are omit ted

unless they are absolutely necessary to completely

describe the object.

STEPS

5. Darken visible lines.



18/27

ME 101

Dr. Ouzhan Ylmaz

g

Isometric drawing: object has inclined surfaces

W

H

D

y

x Front View

y

x

Nonisometric line



19/27

ME 101

Dr. Ouzhan Ylmaz

g

Isometric drawing: object has inclined surfaces

Nonisometric line

A

A x

y

x

xB

B

AB

C

C

C

x

y



20/27

ME 101

Dr. Ouzhan Ylmaz

g

Isometric drawing

A

A

B

B

C D

E

D

EF

F

x

y

Front View

Regular

C

Reverse



21/27

Dr. Ouzhan Ylmaz

Drawing of Circle and Arcs

In isometric drawing, a circle appears as an ellipse.

2. Construct an isometric square.3. Sketch arcs that connect the

tangent points.

Sketching Steps

1. Locate the centre of an ellipse.



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Dr. Ouzhan Ylmaz


3. Construct a perpendicular

bisector from each tangent point.

4. Locate the fourcentres.

5. Draw the arcs with these centres

and tangent to isometric square.

Sketching Steps

Four-centremethod is usually used when drawn an

isometric ellipse with drawing instrument.

2. Construct an isometric square.

1. Locate the centre of an ellipse.



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Dr. Ouzhan Ylmaz




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Dr. Ouzhan Ylmaz


Half circleQuarter circle



25/27

Dr. Ouzhan Ylmaz

Drawing of Irregular curves in Isometric drawing

1. Construct points along the

curve in multiview drawing.

2. Locate these points in theisometric view.

3. Sketch the connecting lines.

Steps



26/27

Dr. Ouzhan Ylmaz

Hidden lines in Isometric drawing

In isometric drawings, hidden lines areomitted unless they are absolutely

necessary to completely describe the

object. Most isometric drawings will not

have hidden lines.

To avoid using hidden lines, choose themost descriptive viewpoint.

However, if an isometric viewpoint

cannot be found that clearly depicts all the

major features, hidden lines may be used.



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Dr. Ouzhan Ylmaz

Center lines in Isometric drawing

Centerlines are drawn only for showing symmetry or fordimensioning.

Normally, centerlines are not shown, because many isometric drawings are usedto communicate to nontechnical people and not for engineering purposes

isometric drawing1

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